1963 Chevy II Station Wagon Tune Up - From Good To Better

Fine-Tuning a Surf Wagon

The phrase “you don’t know what you’re missing” comes to mind when we think of what happened when we set out to tune up Markas Platt’s ’63 Chevy II station wagon at Westech Performance Group in Mira Loma, California. Even when you think your car is running the best it possibly could, an expert can always show you how to improve it. After driving Platt’s Nova wagon for a couple of days we were impressed with how smooth it ran, without realizing how much smoother it could run.

Platt’s station wagon is exactly what we picture when we think of a surf wagon, and it turns out, that’s exactly what it gets used for—transporting Platt’s surf gear to various spots along the Southern California coastline. It cruises with a solid powertrain recipe consisting of a 350ci crate engine from Chevrolet Performance, backed by a 700-R4 transmission, and good list of reliable performance parts that are perfect for a hot rod wagon that gets driven often. At the helm of this streetable engine combo—what essentially dictates the engine’s behavior—is Holley’s 670-cfm Street Avenger carburetor with vacuum secondaries. When the car was converted to V-8 power in 2011, the carburetor was basically pulled out of the box and bolted to the manifold—no tuning or tweaking whatsoever. The fact that this combination ran so well without any jet changes is great, but we always felt there could be something left on the table.

2/17

Driving the car on the first real hot day in SoCal for 2012 had some slight concern churning in our minds, but the sensation of leisurely cruising down the 60 freeway in a comfortable muscle wagon quickly drowned those thoughts away, and the 195-degree temps reading steadily throughout the drive (even up steep grades) and smooth acceleration had us wondering what, if any improvements could be made to this well-planned, functional hot rod wagon.

“I have never seen one come in that’s perfect,” tuner Ernie Mena said, after we boasted how well the car drove on the way to the appointment, “so I’ll be very surprised if I can’t make it run better than it does.” Turns out after our first baseline pull, Platt’s Nova wasn’t running as impeccable as we thought.

Sources

MORE PHOTOS

VIEW FULL GALLERY

xclose

1963 Chevy II Station Wagon Tune Up - From Good To Better

Here’s a shot of the engine we’re running in the Nova wagon: a reliable “DeLuxe” 350 from Chevrolet that makes an advertised 290 hp. A Holley Street Avenger carb, Sanderson block hugger headers, and a Summit HEI distributor are the main stars underhood, while an overdriven automatic makes cruising on the SoCal freeways a breeze.

One of the first things that Mena tweaked before was the idle adjustment. Although it wasn’t far off, it wasn’t ideal. “It was idling a little too high when it came in and that can waste a ton of fuel if not dialed in properly,” Mena says. Mena made sure to screw the main idle adjusters in all the way before backing them out 11/2 turns, equally.

Platt runs a 180-degree thermostat in his Nova, so we were curious to see the temperature hovering above 200 degrees on the way out to Westech. We suspected possibly a timing issue, but the end tanks seemed to be seeping, which would cause the cooling system to lose pressure and, in turn, efficiency.

We were impressed with how well Holley’s Street Avenger carb ran after learning it had never even had the float bowl off of it. Although Mena did step up the jet sizes after a couple pulls on Westech’s SuperFlow chassis dyno, it ran great for over a year before we decided to see exactly what the air/fuel ratio was.

The wagon laid down 236 hp and 283 lb-ft of torque on its initial pull, but we hoped to improve those numbers by dialing in the timing and air/fuel ratio. A paper air filter, composite flex fan, and a heat-holding tight engine bay could be sapping some power from the crate engine, but we also have to keep in mind this car runs the overdriven 700-R4 transmission, which is known to soak up more power than a standard three-speed auto. For the most part, Mena said the wagon’s numbers were adequate, but he discovered after one pull that it was incredibly lean (15.6:1) at low rpm so a jet change was in order.

Taking the front float bowl off of the Holley Street Avenger for the first time revealed 0.036 main jets, so in order to resolve the lean condition, Mena stepped up four sizes to 0.039 main jets. A confident nod from Mena during the next pull indicated its air/fuel ratio was closer to ideal.

Checking the ignition timing revealed the 350 was set at 39 degrees, which we were surprised about at first since we’re used to 34-36 degrees on small-blocks, but Mena explained since this engine has cast-iron heads and an older combustion chamber design, it “liked” that much. Mena tried retarding, as well as advancing the timing a few degrees, but the numbers were unaffected.

Holley hit the nail on the head when they named the mechanism for their vacuum secondary the “No Trouble” design. Compared to how you used to change the spring in the secondary, this is a snap. Mena opted to change the spring from “purple” to a stiffer “black” one. According to Holley, the secondary springs regulate the opening point and rate based on venturi air velocity. From heavy to light, these black, brown, plain, purple, yellow, short yellow, and white springs affect how the secondaries kick on. Holley recommends starting with the black spring and working your way down. When you can feel the secondary come in hard, go back to the previous spring until the acceleration feels smooth.

Because part-throttle driving is important for a beach-bound cruiser, Mena made sure to hold the 350’s revs at all the common rpm ranges. At 2,500 rpm, the air/fuel ratio was a happy 13.0:1 once the jets were changed.

Since the 670-cfm Avenger we’re running on this combo had never been tweaked, Mena made sure the float levels were where they were supposed to be. To check this without fuel bowl sight plugs (which are found on other Holley models), remove the brass plug with a flat head screwdriver and bump the car until you see a bit of fuel spill out. Upon checking the rear bowl, Mena found the fuel level was low and bumped it up. The float levels are critical for cars with harsh acceleration or for those who often park on steep grades.

With the main jets, initial timing, secondaries, and float bowls finely tuned, Mena also wanted to check out the vacuum advance situation, as he noticed it was plugged at the distributor. Mena explained we could be missing on some increased fuel mileage and smooth engine operation with it plugged.

With the HEI cap removed, the mechanical advance mechanism was exposed to see if Mena could modify it. An ignition advance mechanism adds some timing at low speeds and then “bleeds” it off as you get closer to wide-open throttle. Since this is a true vacuum advance and not a mechanical one, he was forced to simply hook up the vacuum line to see if that improved the wagon’s drive characteristics.

While fitting the necessary line to the vacuum advance, Mena explained that some cars can surge at low speeds with the advance hooked up. Putting a timing light on the engine with the vacuum advance hooked up revealed 52 degrees at low cruising speeds. That much timing is fine for cruising with a mild engine, but Mena explained that hopped-up engines with aftermarket cams and cylinder heads oftentimes need an advance that’s specifically tailored for the application, otherwise too much timing can cause surging at cruising speeds.

On the testdrive, we immediately noticed a smoother idle and more response from a dead stop. By remedying the lean condition, hooking up the vacuum advance, and dialing in the timing, Mena claimed we’ll definitely see an improvement at the gas pump. It still ran between 195 and 210 degrees, but we think that comes from a seeping radiator and power-robbing composite flex fan. Maybe a cooling system upgrade and test is in this project’s future.

The horsepower and torque stayed right around 236/283, despite Mena’s timing and jet changes. We weren’t disappointed; we were just looking to improve driveability, any power improvements would of just been a bonus. We always learn something after spending the day at Westech, so we’d like to offer some advice: If you think your car is running perfect, put it on a chassis dyno—you might be surprised how much better it can run when a pro can work his magic, you won’t regret it. CHP

Tom swapped the original inline six for a 396 V-8, rebuilt with a .030-inch overbore, 9.0:1 compression ratio pistons, a Comp Cams camshaft, and three-angle valve job. Induction is via an Edelbrock 750 on an Edelbrock Performer manifold, and HEI ignition provides the spark. S&S block-hugger headers lead to 2 1/2-inch exhaust pipes and Flow Tech mufflers. A 700-R4 automatic is controlled by the original column shifter. - Super Chevy Magazine » Read More